US1510253A - Spark plug - Google Patents

Description

Sept. 30 1924.

of A. Bor-:HM

SPARK PLUG Filed Nov. 24

NVENTR. BVM

ATTORNEY.

Patented Sept. 30, 1924.

UNITED STATES osea-n. AA.- Bonnn, "onrrnwv Yoma N. Y;

A sranx Intro.

. application med novelie'r a4, 1920. lserial No. 426,242.

To all wko/m. t may concern:

Be it known that I, OSCAR A. BoEHM, a citizen of the United States of America, residing atNew York, county of New York, and State of New York, have invented certain new and useful Improvementsin Spark Plugs, of which the following is a specification.

My invention relates to sparkplugs such as are used for ignition purposes, particularly in connection with internal combustion engines.

The object of my invention is to provide a spark plug which (without the use ofauxiliary spark gaps) will exhibit a lumlnous effect when in normal operation, sucheiect being absent when the plug fails to operate for any reason. Another object of the 1nvention is to provide a very simple, strong, and inexpensive construction which will be practically'leakproof and `free from shortcircuit troubles.

Two typical embodiments of my inventlon are illustrated b the accompanyin drawings, in which Fig. 1 is an outside view of a spark pluor constructed vaccording to my myention; Fig. 2 is a longitudinal sect1o n thereof on line 2-2 of Fi 1; Fig. 3 1s a cross section on line 3 3 o Figs. 1 and 2; Fig. 4 is an end view looking in the direction of the arrow 4 in Fig. 1; Fig. 5 is a longitudinal section of another form of my invention on line 5-5 of Fig. 6, the latter being an end view thereof ooking in the direction of the arrow 6 in Fig. 5.

The improved spark plug comprises a tubular metal body having the usual screw thread 10 for securing the spark plug to a support, enerall the c linder head of the engine. Said bo y also as the usual an ular portion 11 for the applicatlon o a wrench, and a bent wire or electrode 12 near the free end of the threaded portion 10. The inner surface of said tubular body is tapered outwardly, its diameter being greatest at the threaded portion 10. Preferably said tapering inner surface is made with longitudinal ribs 13.

Within the tubular body is arranged the tubular carrier 14 for the mner electrode 15, the latter being a rod or wire disposed axially and preferably -projectinl beyond the inner ends of the body and of e carrler 14,

l'in operation.

indicate that no spark is being produced.

the outer electrode 12 being in this case located to one side of the inner or central electrode. This carrier 14 is made of glass or other suitable resistant material which is a non-conductor of electricity and pervious to light (transparent or translucent). The outer surface of the carrier 14 is tapered at thel same angle as the inner surface of the metal body, or approximately so, and a portion of said carrier has an external diameter greaterthan the smallest internal diameter of the metal body (at the outer end), so that the carrier 14 may be wedged tightly within the metal body, as shown. A layer 16 of suitable cement is placed between the adjacent surfaces of the body and of the carrier. The .ribs 13 form grooves which cause the cement to'dry more quickly, in the manufacture of the plug. The bore of carrier 14 of larger diameter than the electrode 15, leaving a free space or chamber 17 between the said electrode and the wall of the carrier.

The inner end of the carrier 14 is open, so

tween the electrodes 12, 15. The 4outer end of the tubular carrier 14 is closed in any suitable manner, as by means of a metal cap 18 fitted to said end and to the threaded outer end 15 of the electrode 15, a filling 19 of suitable cement being appliedat this point to hold said electrode in place firmly. The threaded end 15 also receives the wire connection and clamping nut which have not been shown, as they may be of usual construction.

A 'spark plug of this construction will not crack, is practically leakproof, and will not short-circuit, and is inexpensive to manufacture. Every time a spark 'um s be tween the electrodesl2, 15, thec am er 17 will become luminous, and since the carrier 14 is pervious to light, the luminous ect will be plainly visible while the engine is Absence of this effect will It will be noted that my invention affords a ready means for testing or watching the operation of the spark plug continuously, without disconnecting the `plug ,from the circuit and without the use of auxiliary les spark gaps or like expedients which increase the consumption ot current or have other drawbacks.

The carrier 14 of Figs. 1 to 4 is tapered for the full. length of the metal body and cemented to the entire inner surface of said body. ln Figs. 5 and 6, the carrier'l has a contracted inner portion 14'. which is spacedv from the metal body to form an annular chamber 20 open at the inner end, this arrangement being preferred in many cases. `lin this second form of my .invention the carrier 14 is cemented to the inner surface of the metal body onlyffor a portion of the length of said body. The ribs 13 in this case need not extend to that portion of the metal body which is adjacent to the contracted portion '14". Another di'erence consists in the fact that in Figs.

5 and 6, the inner end of the carrier is even with the inner end ot the metal body, Where- .Micasa as in Figs. 1 to 4 the inner end of the carrier 14 projects beyond the inner end ofthe inetalv body.

Various modifications may be made Without departingfrom the nature of my invention as set forth in the appended claim. l claim:

A spark plug comprising a tubular body adapted for connection With a support and having an outwardly tapering innen surface provided with longitudinal ribs, a tubular carrier closed at its outer end and vopen at its inner end, said carrier being set Within said body and having a tapered outer surface corresponding to the tapered inner surface ofsaid body, and an electrode extendingv through said 4carrier and supported thereby.

lin testimony whereof I have aHiXed my.

signature.

OSCAR A. BOEHM.

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